Rover owners: Making radiator blanking plates and ductworks; 2nd version (picture heavy)

I previously made a set of plates up to close the gaps around the radiator to promote better flow to the core, but decided recently to revisit these.

My new versions are deeper and should do a better job. They also needed to be revised for my upcoming bonnet vent.

Why you might want to do this is that gaps around the radiator give these effects;

a. the radiator is a source of resistance to the incoming air flow from the bumper and air will take a path of least resistance around it when it can, so the velocity of air over the surface is reduced, with a complimentary drop in heat transfer.

b. the 'escaping' air becomes underflow - this is air that moves under the car joining with that which already goes under - which leads to a larger mass of air under the car, which moves faster, causing more surface drag, which then spills up the sides of the car to the low pressure areas over the rear quarter panels and hood area, mixing with the fast moving air and creating large vortices. These are major aerodynamic drag sources on most cars.

If there was an engine behind this it would be mitigated only by the flow breaking up along the surfaces of the components, and with most new front engined cars you'll find a long undertray that seeks to diffuse this flow out gradually and prevent it from expelling as a big lump.

These cars have a sloped panel that simply directs it down, which is not ideal (but practical for keeping a spare wheel).

The radiator gaps are shown here:

After a few goes with a cardboard template I made up these plates:

Then put the bend in them:

These are then fed in behind the bumper bar and rotated into place:

And some paint:

The bottom of the radiator needs closed off as well, to prevent stagnating flow trying to exit by the gap under the crossmember.

This was done by card board template

The part can them be made up in plastic or metal (it looks bigger on one side, but this is an optical illusion as it is not)

On the crossmember are two captive nuts. I suspect they are there for air conditioning parts to be added (please advise/correct as necessary) and they are ripe for making a rear fixing for the lower duct sheet.

This shot is from underneath - you can see the front subframe jacking loop.

This shot shows a temporary plate made from an old exhaust gasket, but you would use a nice piece of long thin plate to make the lower duct's rear fixing;